Amplifier



FIG. 1 is a perspective view of the ornamental design of the present invention;

FIG. 2 is a top view of the ornamental design of the present invention;

FIG. 3 is a front elevation view of the ornamental design of the present invention;

FIG. 4 is a rear elevation view of the ornamental design of the present invention;

FIG. 5 is a right elevational view of the ornamental design of the present invention;

FIG. 6 is a left elevational view of the ornamental design of the present invention; and,

FIG. 7 is a bottom view of the ornamental design of the present invention. 

The ornamental design for an amplifier, as shown. 